Fuel injection assembly for an internal combustion engine

ABSTRACT

A fuel injection assembly for an internal combustion engine has a fuel injector, an injector cup and a holding element for securing the fuel injector in the injector cup, wherein the fuel injector has an annular groove defined in part by an annular flange having a profiled peripheral surface engageable by a profiled surface on the arms of a holding element when the fuel injector is secured to the injector cup, to provide a line or point contact between the fuel injector and the holding element.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to European patent application No.16182709.2 filed Aug. 4, 2016, the contents of which are herebyincorporated by reference herein.

FIELD OF INVENTION

The present disclosure relates to a fuel injection assembly for aninternal combustion engine, particularly but not exclusively, to a fuelinjection assembly for use with a high-pressure common rail fuel supplysystem for a multi-cylinder internal combustion engine. The disclosurealso relates to a method of assembling a fuel delivery systemincorporating a common rail fuel supply for a multi-cylinder engine.

BACKGROUND

A common rail fuel supply system includes a reservoir of fuel on thehigh-pressure typically in the form of an elongate tube having a fuelreservoir which is also known as a main gallery. Fuel injectors,typically one per cylinder, are connected to the common rail at spacedintervals through an injector cup which is typically connectedmechanically and hydraulically directly to the common rail. In a knownsystem, the fuel injector is located in the injector cup and is securedin position in the injector cup by means of a connection plate which iscoupled to the fuel injector cup through two bolts. This knownarrangement worked satisfactorily but has the disadvantage that itrequires a significant amount of space in an environment such as in avehicle where space is extremely limited. There are also difficulties inensuring that process parameters such as the tightening torque on thebolts is accurately carried out. As a result, this solution is expensiveand time consuming to assemble and not suitable for many applications.U.S. Pat. No. 8,479,710 B2 discloses a fuel injector system in which acoupling structure is provided for coupling a fuel injector to aninjector cup, in which the cup has diametrically opposite slots in aperipheral wall for receiving clips which engage an injector to locatethe injector in the cup. The clips are held in position by a retainerband which is fastened over the clips. The use of these severalcomponents is costly, complicates assembly and mitigates againstsubassembly of the components since the components need to be held inposition on the cup for transportation but have to be disassembled forthe injector to be inserted. A further problem arises in that it isdesirable for the injector to pivot slightly in the cup and to maintaincontact with the securing device in order to prevent radial loads on theinjector generated by the fuel pressure during the fuel injection phase.

SUMMARY

According to example embodiments of the present invention, there isprovided a fuel injection assembly for an internal combustion engine,the assembly having a longitudinal axis and including an elongate fuelinjector, an injector cup and a holding element for securing the fuelinjector to the injector cup. The injector cup extends along thelongitudinal axis, the injector cup and has an upper end and a lowerend, the injector cup having a recess in its lower end adapted toreceive a fuel inlet port of the fuel injector such that a fuel outletport of the injector projects from the lower end of the injector cup, afirst opening or openings being formed in the peripheral wall of theinjector cup for receiving the holding element. The holding element isgenerally U-shaped having two generally parallel arms adapted to engageopposite sides of an annular groove in the fuel injector to secure thefuel injector in the injector cup. The annular groove is defined in partby an annular flange having a profiled surface engageable by a profiledsurface on the arms of the holding element when the fuel injector issecured to the injector cup, to provide a line or point contact betweenthe fuel injector and the holding element.

It can be seen that the side of the flange defining the groove is curvedboth by the radius of the fuel injector and the curve of the flangeperpendicular to the radius to provide a profiled surface, including apart spherical contact surface which engages with the profiled surface,including a flat planar surface, of the chamfer on the holding element.In this way, a point or line contact is provided between the fuelinjector and the holding element which enables the injector to easilypivot relative to the holding element and the injector cup. Thiseffectively prevents radial loads being applied to the injector when itis mounted into the engine and subjected to fuel pressure. Furthermore,the part spherical-to-plane contact facilitates the ease of positioningthe correct angular position of the fuel injector relative to theinjector cup during initial assembly. Thus, the present arrangementprovides an improved method of providing a suspended fuel injectorsystem compared to the known solutions and does so in an efficient andeconomical way.

Preferably, the injector cup has a further opening or openingsdiametrically opposite the first opening for receiving the outer ends ofthe two arms.

In an example embodiment, the holding element has a part adapted to abutthe outer surface of the injector cup when inserted therein to definethe installed position of the holding element.

A further embodiment includes an indexing clip which has resilient armsengageable with an engagement surface on the injector cup to locate theclip accurately on the cup and further including a protrusion projectinggenerally perpendicularly from the resilient arms and engageable in arecess in the fuel injector to lock the fuel injector in a desiredangular position relative to the injector cup.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment in accordance with the disclosure will now be described byway of example with reference to the drawings, in which:

FIG. 1 shows an exploded view of a fuel injector cup and fuel injectorassembly,

FIG. 2 shows a perspective view of the assembly of FIG. 1,

FIG. 3 shows a perspective view of a holding element,

FIG. 4 shows a scrap view of the holding element and an indexing clip,and

FIG. 5 shows an external view of the fuel injector cup and fuel injectorassembly.

DETAILED DESCRIPTION

In this description reference is made to upper and lower ends but thisnomenclature is used solely for descriptive convenience. In theinstalled condition, the orientation of the assembly depends upon theparticular configuration.

FIGS. 1 and 2 show a fuel injector cup 2 for receiving a fuel injector4, the cup including a generally cylindrical body having, in thisembodiment, an arcuate cutaway 6 adjacent its upper end through whichthe cup 2 is fastened to a tubular fuel rail (not shown) in amechanically secure and hydraulically fluid tight manner. In alternativeembodiments (not shown), the cup may be fastened to the fuel supply byalternative connections such as a connection on its top face. At itslower end the cup 2 has an opening for receiving the fuel inlet 10 ofthe fuel injector 2. The fuel injector inlet 10 engages with thehydraulic connection to the fuel rail to provide a direct fuel pathbetween the common rail reservoir and the injector 4.

The injector cup 2 has, adjacent its lower end, at least one spaced slot12 adapted to receive in a push fit, for manual assembly, respectivearms 14 of a holding element 16, to be described with reference to FIG.3, and on the opposite side of the cup 2 there is at least onesupporting slot through which the outer ends 18 of the arms 14 pass. Thearms 14 are resilient and their outer ends 18 are arranged to deflectagainst the resilience as they enter the supporting slots 20 to firmlyhold the holding element 4 in position in the injection cup.

Referring now to FIG. 3, there is shown a perspective view of theholding element 16 which is a U-shaped member and has two generallyparallel arms 14 joined by a web 22 which, in this embodiment, is curvedwith a radius substantially the same as the circumferential radius ofthe injector cup 2. The web 22 abuts the outer surface of the injectorcup to determine that the holding element is fully inserted. The holdingelement 16 is formed of a resilient metal material. On their inner topedges (as shown) each arm 14 has a profiled surface in the form of achamfer 24 along its length to form a surface at an angle to the facesof the arms. The chamfer surface 24 may be flat or may be a convex orsimilar curve.

The inner edges of the outer ends 18 of the arms 14 each have a chamferwhich serve to guide the arms into the supporting slots, the slots beingpositioned and dimensioned to deflect the arms outwardly against theresilient bias to thereby secure the holding element 16 firmly inposition.

Referring now to FIG. 1, the fuel injector 4 has a peripheral annulargroove 28 into which the arms 14 of the holding element 16 engage onopposite sides of the injector 4. On its upper side the groove 28 isdefined by a flange 30 which has a profiled surface, which may bearcuate, both about the axis of the injector and about an axisperpendicular to the injector axis. When the holding element 16 isinserted, the chamfer 24 contacts the curved profile on the flange 30.Because of the curved profile only a point or line contact is madebetween the fuel injector 4 and the holding element 16 and this enablesthe fuel injector 4 to pivot easily during assembly to a position whereradial forces on the injector 4 during fuel injection are minimised.

In order to ensure that the fuel injector 4 has the correct angularalignment in the combustion chamber to ensure the correct sprayorientation during injection, an indexing clip 32 is provided formed ofa metal, although in other embodiments it may be formed of a plasticsmaterial, the clip 32 having two resilient arms 40 which wrap round theoutside of the injector cup 2 and engage in recesses or orifices in thecup wall to accurately locate the clip 32 on the injector cup 2. Theclip 32 further engages the web 22 of the holding element 16 to preventthe holding element from moving out of the injector cup 2. The indexingclip 32 has a downwardly extending protrusion 34 which, during assemblyby pivoting the fuel injector relative to the cup enables the protrusion34 to engage with a recess 36 in the fuel injector body to therebyaccurately secure the injector 4 in the correct angular position.

FIG. 5 shows the injector cup 2 and fuel injector 4 in the assembledcondition with the fuel injector 4 extending from the injector cup 2 soas to enter the combustion chamber when the injector cup 2 is secured tothe engine. This arrangement is referred to as a suspended injectorsystem in which the injector is not mechanically connected to theengine. This results in less transmission of noise from the fuelinjection process. The indexing clip 32 accurately locating the injector4 is shown together with an electrical connection block 38 for supplyingthe electrical fuel injection control signals.

The present disclosure greatly facilitates assembly compared with knownarrangements, since once the fuel injector 4 is pushed into the injectorcup 2, the holding element 16 is pushed into place, and the indexingclip 32 is clipped over the injector cup to align the fuel injector andthe assembly is complete.

The invention claimed is:
 1. A fuel injection assembly for an internalcombustion engine having a longitudinal axis, the fuel injectionassembly comprising: an elongate fuel injector having a fuel inlet port,a fuel outlet port, an annular groove and an annular flange; an injectorcup; a holding element for securing the fuel injector in the injectorcup; and a plurality of spaced slots integrally formed as part of theinjector cup; wherein the injector cup extends along the longitudinalaxis, the injector cup has an upper end, a lower end and a peripheralwall, the injector cup having an opening in a lower end thereofconfigured to receive the fuel inlet port of the fuel injector such thatthe fuel outlet port of the fuel injector projects from the lower end ofthe injector cup, the holding element being generally U-shaped havingtwo generally parallel arms, each of which is engaged with acorresponding one of the plurality of spaced slots, and the twogenerally parallel arms configured to engage opposite sides of theannular groove in the fuel injector to secure the fuel injector in theinjector cup, each arm of the holding element including a profiledsurface; and wherein the annular groove is defined in part by theannular flange having a profiled surface engageable by the profiledsurfaces of the arms of the holding element when the fuel injector issecured to the injector cup, to provide a line or point contact betweenthe fuel injector and the holding element.
 2. The fuel injectionassembly according to claim 1, wherein the profiled surface of theflange is curved in two mutually perpendicular planes.
 3. The fuelinjection assembly according to claim 1, wherein the profiled surface onthe arms of the holding element comprises a chamfer inclined relative toan upper surface of the respective arm.
 4. The fuel injection assemblyaccording to claim 1, in which the injector cup has a further opening oropenings diametrically opposite the first opening for receiving theouter ends of the two arms.
 5. The fuel injection assembly according toclaim 1, wherein the holding element has a part configured to abut anouter surface of the injector cup when inserted therein to define aninstalled position of the holding element.
 6. The fuel injectionassembly according to claim 5, wherein the part of the holding elementconfigured to abut the outer surface of the injector cup comprises a webjoining the two arms.
 7. The fuel injection assembly according to claim1, further including an indexing clip which has resilient armsengageable with an engagement surface on the injector cup to locate theindexing clip accurately on the cup and further including a protrusionprojecting generally perpendicularly from the resilient arms andengageable in a recess in the fuel injector to lock the fuel injector ina desired angular position relative to the injector cup.
 8. A fuelinjection assembly for an internal combustion engine, the fuel injectionassembly comprising: a fuel injector having a fuel inlet port, a fueloutlet port, an annular groove and an annular flange; an injector cupincluding an upper end, a lower end, a peripheral wall, and an openingdefined in a lower end thereof which is configured to receive the fuelinlet port of the fuel injector such that the fuel outlet port of thefuel injector projects from the lower end of the injector cup; a holdingelement configured to secure the fuel injector in the injector cup; anda plurality of spaced slots integrally formed as part of the injectorcup; wherein the holding element being generally U-shaped having twogenerally parallel arms, each of which is engaged with a correspondingone of the plurality of spaced slots, and the two generally parallelarms to engage opposite sides of the annular groove in the fuel injectorto secure the fuel injector in the injector cup; wherein the annulargroove is defined in part by the annular flange having a profiledsurface which is configured to engage the arms of the holding elementwhen the fuel injector is secured to the injector cup, so as to providea line or point contact between the fuel injector and the holdingelement.
 9. The fuel injection assembly according to claim 8, whereinthe profiled surface of the flange is curved in two mutuallyperpendicular planes.
 10. The fuel injection assembly according to claim8, wherein each of the arms of the holding element includes an uppersurface and a profiled surface, each profiled surface of the arms of theholding element comprising a chamfer inclined relative to the uppersurface of the respective arm.
 11. The fuel injection assembly accordingto claim 8, wherein the injector cup has a further opening or openingsdiametrically opposite a first opening of the injector cup, the furtheropening or openings configured to receive outer ends of the two arms.12. The fuel injection assembly according to claim 8, wherein a part ofthe holding element abuts an outer surface of the injector cup wheninserted therein to define an installed position of the holding element.13. The fuel injection assembly according to claim 12, wherein the partof the holding element comprises a web joining the two arms.
 14. Thefuel injection assembly according to claim 8, wherein the injector cupincludes an engagement surface, and the fuel injection assembly furthercomprises an indexing clip which has resilient arms for engaging theengagement surface the injector cup to locate the indexing clip on thecup, the indexing clip including a protrusion projecting generallyperpendicularly from the resilient arms to engage in a recess in thefuel injector to lock the fuel injector in a desired angular positionrelative to the injector cup.